1. Field of the Invention
The present invention relates to an endoscope equipped with a mechanism for cleaning a scope end where exposed ends of optical devices such as object lens and light guide are located and, more particularly, to such a scope end cleaning mechanism in which water injections, air inhalation and air exhalation are utilized.
2. Description of the Background Art
A conventional endoscope, either of fiber scope type or of electronic endoscope type, is usually equipped with a mechanism for cleaning contamination due to gastric juice of a scope end where exposed ends of optical devices such as object lens and light guide are located, which normally comprises a water injection to wash out the gastric juice on the scope end and an air exhalation or blowing to blow away remaining water drops from the scope end.
Such a cleaning often includes additional air inhalation for the purpose of reducing a gastric inner pressure increased by the water injection and the air exhalation, as an increased gastric inner pressure is known to cause some pain for a patient at a level which varies for different patients.
A sequential operation of such water injection, air exhalation and air inhalation has conventionally been carries out by an operator who controls separate switches provided for activating each of these functions. Thus, a painless cleaning operation depended very much on the operator's skill.
The skill of the operator becomes also essential in such a conventional endoscope in a view that an abrupt dropping of 8 to 15 Torr in the gastric inner pressure by the air inhalation can produce dew condensation due to a dropping of dew point, which will obstruct a satisfactory observation by befogging the optical devices at the scope end.
Furthermore, as it has become a fairly common practice in an endoscope to make various adjustments and modifications on directly observed images, securing of a stable condition for direct observations becomes a matter of great concern, but this can also be affected by the operator's skill in a conventional endoscope because of the problem of dew condensation just mentioned.